Telephone-exchange system



March 16 1 926.

E. JACOBSEN TELEPHONE EXCHANGE SYSTEM Filed Nov. 18, 1920 '7 Sheets-Sheet 1 F/qJ. H. 12. i7 3. {7 2.4 04,5 H 16. 1 7 .7

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E. JACOBSEN TELEPHONE EXCHANGE SYSTEM Filed NOV. 18, 1920 '7 Shts-Sheet 6 March 16 1926.

E. JACOBSEN TELEPHONE EXCHANGE SYSTEM 7 Sheets- Sheet '7 Filed No'v. l8, 1920 m venfoh [/rfl/ Jacas e1 Patented Mar. 16, 1926.

LINKED TATES iFFIQE.

PATENT EMIL JACOBSEN, OF PGRT WASHINGTON, NEVJ YORK, ASSIGNOR TO AMERICAN TELE PHONE AND TELEGRAPH COMPANY, A (lQBPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Applicationfiled November 18, 1920. Serial Nb. 424,941.

To all whom 112? may concern:

Be it known that I, EMIL JACOBSEIN,1GSlCl ing at Port \Vashington, in the county of Nassau and State of New York, have invented certain Improvements in Telephone-En change Systems, of which the following is a specification.

This invention relates to telephone eX- change systems and particularly to toll trunking, wherein thetoil connections are partially built up over automatic switches.

Its object is to provide a' telephone eX- change system of this character which will take care of various classes of calls, and wherein some or all of the substations are equipped with coin boxes in which a coin or coins must be deposited before the operator allows the parties to talk,- these coins being then collected or refunded bythe operator at her will.

In the system of'this invention a local pay station subscriber desiring atoll-call removes his receiver and operates his dial to cause his line to be automatically extended to a recording operators position. The operator then gets the number ofthe calling line and the esired number from the calling subscriber. The cord circuit to which the calling line is extended by the toll operator is equipped with a key Wl110l1 may now be operated by the operator to cause tone to be transmitted from apparatusindividual to the calling line to the operators head set to inform her of the character of thecalling line. The recording operator now breaks down the connection from the calling line to herposition and communicates with a toll operator.' This operator has access to toll selectors which are equipped with transmission apparatus suitable for long distance connections. The recording operator passes to the toll operator the information she socured from the calling subscriber and the toll operator then proceeds to order up, the connection for the desired distant subscriber.

When this connection has been built up the toll. operator proceeds to build up a connection to the originating subscribers line over the toll selectors and a conn ctor. One of these toll selectors as stated, is equipped with transmission apparatus suitable for long distance calls. When the connector tests the line of the originating or calling subscriber and finds it to be busy, it remains set, but no interference with the existing connection results. The busy condition of the originating line is indicated to the toll operator by the flashing of the calling supervisory lamp inthe cord she had used. The tolloperator by this signal knows the line which originated the call has become busy since originating such call. The operator may then attend to other calls. As'soon as the originating line upon which the connector is waiting becomes idle, this condition automatically causes the lamp to cease flashing and remain lighted. The toll operator now by means of a key in the cord can listen for a class tone which is transmitted over the connection she-hasbuiltu-p from the apparatus referred to individual to the said originatingline, and thus may determine for herself to what class the line belongs. She now operates her ringing key which starts the automatic ringing operation at the connector to signal the line of the originating subscriber. Interrupted ringing current is maintained applied and is cut ofl when the party answers whichfresp'onse also causes the eXtinguishnient of the calling lamp. The operator now informs the party that the toli connection. he asked for has been completedand asks him to deposit the required coins. She is informed ofthe denomination of the coins deposited by gongs which the coins strike in passing into the coin box. The operatornow causes the collection of the coins by operating her collect key which impresses current from a high voltage source upon the line to operate the polarized magnet in the coin box to collect the coins. If, for any reason, the coins-are to be returned she depresses her refund key which causes the said magnet to refund them.

In the case of a toll call incoming to this subscriber the toll operator would build up the connection in the same manner but on dinarily would not require the deposit of coins to allow the subscriber to talk unless the charge is to be reversed, and the'local party agrees to such reversal of the charge, whereupon the operation would be the same as described.

It is desirable in some cases to hold the line of the originating subscriber busy from the time he secures the connection with a recording operators position until the connection, including the toll'selectors and connector, having the required trans mission apparatus for toll calls, is built up to his line in order to prevent a local call from being extended to said subscriber and thus delaying the toll call desired, and also to check the number of the calling party as described. This invention takes care of a call of this character which is known in practice as a two number toll call. In case a local automatic party makes a toll call of this character he reaches a recording operator by dialing a certain code consisting of two digits. The recording operator answers the call with a cord equipped with a class tone key. While holding this key operated, she plugs into a jack terminating in an idle toll selector and proceeds to select the originating line over this and other selectors and a connector. Due to the maintained operation of the class tone key, when the connector tests the line, the automatic switches which extended the originating line in the first in stance to the recording operator are antomat-ically released and the line is thereafter held busy from the toll connector. The call is then extended to the desired distant party by the toll operator.

The system is also designed to take care of calls from one local pay station to any other local station, manual or automatic, with provision for collecting coins from the calling station. These local pay stations are equipped with line'switches which plunge in and seize ranks to the pay station operators position. If the desired line is an automatic line, the operator selects a trunk terminating in a line switch which seizes an idle local first selector and proceeds to build up a connection to the desired line. If the desired line is a manual line, she will simply plug into a multiple jack of the called line. The calling side of the operators cord is equipped with a polarized relay bridge, and an ordinary calling supervisory relay bridge, and a rela governed by the resistance of the sleeves of the jacks connects in the polarized relay bridge on automatic calls and the other bridge on manual calls. When the called party answers the relay thus bridged across the cord extinguishes the calling lamp and the operator depresses a key which impresses current from a high voltage source on the calling line to operate the polarized magnet of the coin box; of the calling station to colleet the coin. If the call. cannotbe completed the operator actuates another key which impresses current from a high voltage source of opposite polarity on the calling line to operate the polarized magnet to refund the coin.

Referring to the drawings, Fig. 1 illustrates a toll operator's cord circuit: Fig. 2 illustrates a toll first selector; Fig. 3 illustrates a toll trai'ismission selector; Fig. slillustraies a combination toll and local connector; Fig. 5 illustrates the calling line, a

To call Q0/1012. 75/20 coins we to be C(JZZr' z/(YZ from local party whether the out! mcoming or outgoing.

A call of this nature would be made by a toll. operator ha ing cord r is as shown 50 ll] in Fig. 1 on an order for a call from a local pay station.

The calling party at such station operates his dial to set a first selector FS (Fig. to select a recording operator who se cures the number of the called par-"y and any other necessary information, which she writes on a ticket. This ticket cclivered to a toll or line operator, who has control of suitable long distance equipment shown in Figs. 1, 2, 3 and l. This type of toll call is termed a long haul toll call.

Referring to Figs. 1, 2, 3, and a, the toll operator will insert plug 100, Fig. 1, into jack 200, Fig. 2, leading to an idle toll fi st selector. Relays A and F then energize over the following circuit: ground, relay A, Fig. 2 armature 219 and back contact of relay 1), relay F, sleeve wire 1.,l, normal contact 102 of the dial key DH. to free pole of battery. Relay A closes an cnei gizing circuit for slow relay l3 and F at its armature and front contact l an additional circuit for slow relay 1%. lay B, in attracting its upper arinatn lights the lamps 205 associated with inulti ples of jack 200 to inform the other o ators that this trunk is busy. The operator will now operate her dial key Din: which. in closing the spring 102 to its allernaie contact will switch the sleeve conductor llli to the free pole of be;-v in series with one side of induction coil 106 and a dial i i proceed to dial the d sired number.

A in responding as the dial rcstoics, inits impulses over the following ci.-.:uit to the first selector vertical magnet, which steps the shaft to the desired level: lrcc pole of battery, magnet 205, slow relax (fl. lei-nor armature and front contact of .T-l mature and back contact of relay 9.. ture 21 1- and back contact of relay l) ground. Relay C, being slow, hold: ing the impulses. A non-.iinlnctive 250 is placed around the windii of rela" to improve the impulse circuit. first step of the shaft oil-normal cor closes, energizing relay E over fro tat. s of relays C and B. ltelay l'l. up i-- tracting its inner armature, locks itsel l. ore:-

the back contact of rotary magnet 211 to ground at the armature. 21 1 of relay D. Upon the cessation of the impulses slow relay C releases and rotary magnet211. receives an impulse in a circuit mcluding the upper armature and front contact of relay E, normal contact of relay C, and-upper armature and front contact of relay B- to rotate the selector onto the first trunk. The arn'ia-ture of magnet 21.1, at the end of its stroke, opens the locking circuit of relay E, whereupon this relay releases openmg the circuit of magnet 211 which releases. It the first trunk is busy ground is present on the test or sleeve multiple 212. This ground is transmitted over test brush 213, armature 218 and back contact of relayD, lower armature and back contact of magnet 211, oilfnormal contact 209 to relay E. Relay E thereupon energizes and closes its locking circuit previously traced. In attracting its upper armature it again energizes magnet 211, which rotates theselector brushes into engagement. with the next trunk, and'at the end of its stroke opens the locking circuit of relay E, releasing the same. Assuming this trunk to be idle' no groundis present onthe sleeve multiple 212 thereof and consequently relay E. is not again energized. The following circuit isnow closed to energize switching relay D; free pole of battery, relay It, contact209, armature and back contact of magnet 211, conductors 215 and 216, relay D, conductor 217 to ground at the upper armature and front contact of relay B. Relay E is marginal and does not operate in this circuit. -Relay D prime extends the tip; and ring conductors of the 'jackto the tip and ring conductors of the seized selector. In attracting its armature. 218, relay D applies a direct ground to test brush. 213 and thence to test multiples 212 to cause the seized trunk to test: busy to other selectors. In attracting its arn'iature 219, relay D extends the sleeve conductor 203 to the brush 220 now connected by multiple 222 to the impulse wire 221 which energizes impulse relay E" of the seized toll selector shown in Fig. 3-. In practice there would be a number of intermediate selectors between the selector of Fig. 2 and that of Fig. 3, the number being determined by the capacity of the exchange. These selectors would be substantially the same as that shown in Fig. 2 and are. therefore omitted. The toll selector of Fig. 3 iimnediately pre codes the connector, Figl, which has access to the desired subscribefls line. Assuming therefore that the connection has been built up to the toll selector ofFig. .3, relay it is energized: over the following circuit: ground, relay. E conductors 301. and 302, armature 341 and back contact of relay B, conductor 30%, impulse conductor conductor 221, multiple tern'iinal 222, brush 22.0,

beingslow, holds the circuit of lamp 205 closed. The circuit-of relay vertical magnet 308 isas follows: lower armatures and back contacts of relays D and E lower armature and front contact of relay I slow rclay G magnet 308 to free pole of battery. ielay G being slow, remains energize-d during the-transmission ofthe impulses. Upon the first vertical step of the shaft, relay H operates over the following circuit; free pole of battery, relay H 05 normal contact 311,

armature and front contact of relay G upper armature and front contact of relay F to ground. telay H thereupon locks 1tself over the following circuit: free pole of battery, relay H contact 311, conductor 312, armature and back contact ofrotary magnet 313, conductor 314, upper armature and frontcontact of relay H to ground at the armature 315 and back contact of relay D These circuits are similar to those traced for the selector of Fig. 2, and, therefore, need not be further described, it being suflicient to say that, upon the cessation of the impulses through the vertical magnet, slow relay G releases and causes the hunting operation to take place, and upon the finding of an idle trunk switching relay D which corresponds to relay D of Fi 2 operates and connects the incoming and out-- going tip and ringconductors together. When slow relay G energized at the begin ning of the impulse series a slow relay C operated by its lower winding over conductor 360 to ground at the upper aru'iature of relay F and in attracting its lowermost ar mature locked itself'to the grounded sleeve wire 307 over a back contact of relay A W lhe connector. of Fig. 4, to which the connection is now extended, is a combination toll and local connector; that is tosay, this switch may be seized either by local selec tors operated by the subscril'iers themselves or by toll selectors, such as shown in F 3, which are operated by the toll operators in connection such as the one beingdescribed. Relay D in attracting its armature 315, closesthe following. circuit to energize relays E v and B of the connector: ground, armature 315 and front contact of relay D upper arn'iature and front contact of relay E conductor 317, brush 318, multiple S19, impulse conductor 4 .02, upper winding of relay E", upper winding of relay B to free pole of battery. Relaydfi operates slow relay C which, in attracting its armature 405, grounds the sleeve conductor 407 to cause this connector to test busy to testing local selectors. This armature in closing its front contact also closes the following circuit: ground, armature 405, conductors 407 and 408, relay F conductor 410, sleeve conductor 404, sleeve multiple 320, sleeve brush 321, conductor 322, arma ture 323 and front contact of relay 1)", armature 324 and front contact of relay C resistance to free pole of liattery. It will be remembered that relay C is locked up to the grounded sleeve condiu-tor 30?. Relay F, in attracting its armature 413, closes a circuit to the lower winding of relay i l. ll hen relay C attracted its armature 405, slow relay 1) operated over the following circuit: ground. armature 405, coir ductor 407, otf-norn'ial contact 4l5, lower winding of relay D to free pole of battery.

The operator now operates the dial D to transmitthe ten series of impulses which intermittently operates relay E Each time the upper armature of relay T1 is retractet and upon each consequent retraction of the armature of relay B a circuit is closed as follows: armature and back contact of relay B armature 420 and front contact of relay G, armature 421 and front contact of relay D conductor 452, armature 423 and back contact of relay J vertical magnet 424 to free pole of battery. The vertical magnet elevates the brushes to the desired level. On the first vertical step of the connector shaft, off-normal contact 415 opens and relay D is thereafter dependent for its energization upon the grounds received from the back contact of relay B through its upper winding. At the end of the series therefore relay D releases, shifting the stepping circuit to the rotary magnet 425. The units impulses therefore will pass from the grounded armature of relay B to the armature 421 and back contact of relay Dficonductor 420, armature 427 and back contact of relay G slow relay H, armature 428 and back contact of relay J, magnet to free pole of battery. Slow relay H remains operated during the transmission of the impulses to disc nnect the test relay G from the test brush 420 during the rotary motion of the switch. Relay l-l in operating, operates the slow relay l. Upon the tern'iination of-the units series of impulses the relay H" releases shortly before the relay 1. Relay G is thus momentarily connected to the test brush 429 and if the line is busy the sleeve multiple 480 thereof will be grounded, closing the following circuit for the test relay free pole of battery, lower low resistance winding of relay G, conductor 43 1, armature 432 and front contact of relay E armature 4 33 and back contact of'relay H", armature and front contact of relay 1, the test brush 429 to ground at the sleeve multiple 430. clay G then locks up over the following circuit: free pole of battery, lower winding of relay G, conductor 431, armature 432 and front contact of relay E armature 433 and back contact of relay H niake-beforc-break contact 434 of relay 1 armature 435 and front contact of relay G", armature 436 and front contact of relay E". conductor 437 to sleeve brush 429 to grounded sleeve multiple 430. Relay (i in attracting its armature 43S, connects busy tone as well as interrupted batte to the ring conductor. leading back to the toll selector. Consequently the following circuit is intermittently closed for relay B" of the toll selector, Fig. 3; free pole of battery, interrupter 4 9, conductor 440, armature 438 and front contact of relay G ring conductors 441 and 328, brush 32:), conductor 330, armature 331 and front contact of relay D conductor 332, contacts and 384, conductor lower winding of relay B to ground. Relay B in attracting and retracting its armatures 336 and 337, removes and applies battery and ground to the tip and ring conductors 338 and 339 leading back to the operators cord, which causes the intermittent operation of supervisory relay 107 and the flashing of the supervisory lamp 108. By the flashing of this lamp the operator knows the line is busy. The apparatus may remain in this condition until the selected line becomes idle and inasmuch as the relay G is maintained operated by the ground on the multiple 430 of the busy selected line, the removal of this ground releases the relay G which, in retracting its armature 438, releases relay B Fig. 3, which maintains battery applied to the tip and ring conductors leading back to the operators cord which causes the continued energization of the supervisory relay 10'. and the sustained lighting of the supervisory lamp 108, whereby the operator knows the line has become idle. Relay G in retracting its armature 442, extends the grounded sleeve conductor 407 through the upper winding of relay J to the test brush 429, and thence to battery through the cut-off winding of the called subscribers line switch thus causing this line to test busy to other connectors and removing the control of the line switch from the selected line. Relay J, in attract ing its armature 448, locks itself to ground on sleeve conductor 407 over conductors 462, 463, 408. In attracting its armatures 423 and 428, relay J cuts off the rotary and vertical magnets. In attracting its armatures 444 and 445, this relay connects the incoming and outgoing tip and ring conductors together. The operator can now listen for class tone on the called line to ascertain to what class of service the station belongs. This circuit leads from the tone coil secondary 520 through the holdin winding 504 of the called station line switch, through the brush 4 9, condenser 446, sleeve conductor 404, sleeve multiple 820, sleeve brnshxl-lfll, conductor822, armature and front contact of reray D condenser 840, conductors 301 and 302, armature34l and back contact of relay '13, conductors 304 and 305, impulse conductor 221, multiple 222, brush 220, conductor 223, armature 9.19 and front contact of relay l), relay F, conduct-or 9.03, sleeve of the jack 200, sleeve of the plug 100, conductor 101, primary winding of induction coil 106 to free pole of battery. The lrey DK when operated opened at contact 105, the shunt about the secondary winding of coil 106. Having secured this information the operator can now cause the called partys bell to be rung. To do this she operates her ringing key K, (Fig. 1), which impresses alternating current over the tip and ring'conductors which operates relay A Fig. 3. Relay A in attracting its armature, unlocks relay C Relay C, in releasing, removes battery at its armature 324 from the sleeve conductor leading to the connector and back contact of relay D armature 4531 and front contact of relay E tip conductor 452, multiple 353, brush arn'iature and back contact of relay 1?, tip conductor 344, armature 345and front contact of relay D contacts 340 and 347, conductor 348, armature 350 and back contact of relay C upper winding of relay C to free pole of battery.

When the called subscriber answers, relay C operates and locks up to the grounded sleeve wire 307 over the circuit previously traced leading over the lower winding of relay C and extends the called line loop to reay B which thereupon operates to cut oil battery and ground from the tip and ring wires leading back to the cord circuit of Fig. 1. which causes the deenergisation of relay 107 and the extinguishinent of supervisory lamp 108 to inform the operator that the 3alled party has responded. In attracting its arn'iature 324 relay C again energized relay F in the connector. Relay F in attracting its armature 448 opens the ringing circuit and connects the incoming and outgoing ends of the ring conductor together.

Relay B in attracting its armature 341 removes the short circuit from about relay 351. In attracting; its zarmature 347-, relay B closes a holding circuitfor relay (Findependent of that lea'ding overtheback contactof relay A in attracting its armature relay B extends the front contact of relay A to relay 1 for the purposepof enabling the operator to signal a P. 131 X. operator. The operator by depressing her listening lrey Ll; may now talk with the subscriber over the connection thus built up, and request him to deposit the necessary coins in a coin box which maybe of thetype shown in Patent 1,043,219,1to 'O; F. Forsberg, issued Novemher'f), 1912. These coins as they are deposited strike gon'gs .in'thecoin box and thus convey to the operator information as to the character of the coins, deposited. The operator n'owhuilds up the connection over the plug 110 in thedirec tion of the calledline, but since this forms no part of the present invention, "it. is not shown. The operator now depresses 'h'er collect lrey GK to cause thedepos'itedcoinsto be collected. The depression of this :key energizes a relay lll whichin attracting its armature connects positive 110 volt batter to the polarizedrelay 351, the shunt about the relay being now open atthe armature 341 of relay B (Fig. 3). Thisrela'y in-respending connects positive .110 voltbattery over both sides of the line from one side of which the polarized relay of the icoin box is connected in a grounded branch '(see Fig. 5').

The polarized'magnet in thecoin box. in;re-

spending to this current collects'thecoins i and disconnects itself from. ground as shown and described in detail in said patent. The springs controlled by relay'351 are arranged to eliminate annoying clicks. .Tallring cur rent is fed to the calling or originating substation, shown for example in Fig. 5.:over the windings of relay-B and to the other or called station from the ethos in which it terminates. The tip and ring conductors 338, 339, and 344, 330 are inductively united by the usual repeating coil R in accordance with the standard long distance practice. Talking current is fed to'the calling substation over the following path: free pole of battery, upper winding of relay B armature 850 and front contact of relay (Econductor 349, upper right-hand winding-of repeating coil 1 contacts 347, 346 of polarized relay 351 armature 845 and front contact of relay D tip conductor 344, armature 34S and "back contact of relay I tip brush 352, tip multiple 353, tip conductor 842, 452, armature 451 and front contact of relay E armature 450 and back contact of relay D tip conductor 453, armature 445 and front contact of relay J, tip brush 45.4, multiple 455 through the substation loop returning on the ring conductor multiple 456, brush 457, armature 2444 and front/contact of relay J, ring conductor 458, ar1nature 449 and back contact of relay D armature 448 and front contact of relay F conductor 441, conductor 328, multiple 355, brush 329, lower armature and back contact of 1 conductor 330, armature 331 and front contact of relay D conductor 332, springs and 334 of relay 351, conductor 335, lower right-hand winding of repeating coil R, lower winding of relay B to ground. After the called party has replaced his receiver at the end of the conversation, the operator can again start the automatic ringing operation at any time by operating her ringing key K which by energizing relay A Fig. 3, unlocks relay C which in retracting its armature 324 releases relay F in the connector which starts the automatic ringing operation and upon response of the called party, ringing is again cut-oil as described. In case the coins were to be refunded the operator would have depressed her refund key RK and thereby energized relay 112 which would have applied negative current from the 110 Volt source to operate relay 351 to apply negative current to the line to operate the polarized relay in the coin box in the other direction to refund the coins as shown and described in said patent.

When the original calling subscriber replaces his receiver, relay B releases again applying battery and ground at its armatures 336 and 337 to the tip and ring conductors leading back to the operators cord circuit. This results in the energization of supervisory relay 107 which in attracting its armature lights supervisory lamp 108 to indicate to the operator the termination of the conversation. In order to release the connection, the operator merely removes plug from jack 200. This causes relay E in the toll selector (Fig. 3) to release which opens the circuit of slow relay F which in closing its lower back contact closes one break in the circuit of the release magnet 356. Relay F releasing its upper armature removes ground from the sleeve conductor 307 leading back to the selector of Fig. 2 which causes release relay D thereat to restore, and also releases relay D to complete the circuit of release magnet 356. Relay F Fig. 2 released when the plug was withdrawn, consequently releasing relay B. A circuit is therefore closed for the release magnet 225 of this selector over off-normal contact 226 and back contacts and armatures of relay B, A and D. Relay E in releasing its upper armature removes ground from tne conductor 317 thus interrupting the circuit previously traced through the upper windings of relays E and B Relay B in releasing its armature releases relay C Relays 0* and B at their lower armatures and back contacts close the circuit of release magnet 459 over. oil-normal contact 460.

In the case of incoming toll calls the toll operator would build up calls to the sub scribers as directed by the distant toll operator in the same manner, but would not require the deposit of coins to allow conversation to be carried on, unless the charges were to be reversed.

A toll call when local party originates the call and is to be charged; his line being helcl busy while the operator sets up a connection to leis line one? z' oll SWJltO/ZGS.

A call of this kind would be what is known in practice as a two number toll call. This type of call is known as a short haul toll call, the switches used by the calling party in reaching the recording operator being used in the conversational circuit, and the calling party remaining on the line until the toll call is built up by the operator who answers the call, no second operator being involved. The call being a short haul call, the equipment at the originating ollice does not need long distance transmission eq .ipment as in the case of the long haul toll call described. The station, as A, desiring a toll call of this character is extent ed to a recording operator by dialing a certain code which will cause the line to be connected over a line switch LS, (Fig. 5), a first selector FS and a second selector SS to the recording operators trunk circuit shown in Fig. 6. This operators position is equipped with cords shown in Fig. 7. This operator responds to the call by inserting the plug 7 00, Fig. 7, into the jack 602, Fig. 6, and secures from the calling party the number of his line and that of the desired line. She then takes a plug 100, Fig. 1 and calls the number of the calling station A (Fig. 5) over the switches shown in Figs. 2, 3, and 4 as described.

VVhen the connector is set on the calling line A, a circuit change is brought about which releases the line switch LS, the first selector FS and the second selector SS, i. e, the original connection from the calling line to the recording operator. Thereafter this line is maintained busy from the connector. The apparatus remains in this condition until the connection has been built up in the direction of the desired distant subscriber over plug 110 as before and when this subscriber has responded the operator by depressing her key K, Fig. 1, will start the automatic ringing operation or the connector, Fig. 4, from which the operations are the same as those previously traced. In this character of toll call however the line of the calling party, is maintained busy and inaccessible to other testing connectors or to other manual operators from the time the call is initiated until the toll connection is broken down.

Considering more in detail the operations involved in the setting up or a connection of this character, the removal 01' the receiver at the substation A closes the following circuit to operate the line switch LS to seize an idle first selector FS: free pole of battery, relay 500, contact 501, tip side of the line, the substation loop, ring side of the line, contact 502 to ground. Relay 500 in attracting its armature closes a circuit for the pull down winding 503 of the line switch which in the well-known manner, operates the line switch to seize the preselected first. selector FS, whereupon impulse relay E operates over the substation loop. In attracting its armaturerelay E operates slow relay F Relay 1? in attracting its upper armature closes a circuit for the holding winding 504 of the line switch and in closing its lower armature prepares a circuit for the vertical magnet 50501 the first selector. While the circuit of the line relay 500 over the substation loop is opened when the line switch operates, this relay is slow to release and holds the pull down circuit 503 closeduntil after relay F operates and closes the circuit oi the holding winding 50%, thus maintaining the line switch operated. The calling party now operates his sender S for the first digit of the code thus interrupting the circuit of the impulse relay E Each time relay E retracts its armature, an impulse is transmitted to the vertical magnet 505 in series with the slow relay G, to lift the brushes of the first selector to the level corresponding to the digit in question. When the sender restores relay E remains energized and, consequentlyrelay re leases. When relay G operated upon the first impulse, it prepared a circuit for relay H which was closed over oft-normal contact 506 on the first step of the selector shaft. This relay thereupon locked up over the following circuit: tree pole battery, relay H conductor 507, off normalcontact 500,

conductor 51,4, armature and back contact of rotary magnet 508, upper armature and front contact of relay H conductor 509 to ground at the lowermost armature of relay 1). When the slow relay G releases at the termination of the impulses, rotary magnet 508 is energized over the inner upper armature of relay H normal contact of relay G upper armature and front cont-act or relay F and rotates the set of brushes on to the first trunk. At the end of the stroke of the rotary magnet, the locking circuit of relay H is opened, which relay inreleasing releases magnet 508. The brushes are now in engagement with the first trunk in the selected group. If this trunk is busy, a ground is present on the test multiple 510 and this ground is transmitted over the test brush 511, conductor 512, uppermost armature and back contact of relay D conductor cuit previously traced to ground at the loW-' ermost armature and back contact of relay D In attracting its inner upper armature,

relay H again energizes the rotary magnet which rotates the brushes on to the next trunk. ground is present on the test multiple 510 andconsequently relay H remains dc-energized, after its locking circuit is opened by magnet 508. Switching relay D however, is now'operated over the following circuit tree pole'battery, relay H contact 506, armature and back contact of magnet 508, conductor 513, relay D conductors 515 and 516 toground at the upper armature and trontcontact of relay F Belay H is marginal and does not operate inthis circuit. Relay D however, operates and places a direct ground from the upper armature of relay F, the uppermost armature of relay D conductors 517, 512, brush 511 to the test multiple of the seized trunk to cause the same to test busy to other selectors. Relay D in attracting its inner armatures, extends the tip and ring conductors of the calling line to the tip and ring conductors of the trunk which terminate in the talking brushes 518 and 510. The extension 0]": the alling line to the second selector SS operates the impulse relay thereat, and since this selector is similar to the tirst selector, it is not shown. The calling party at the substation A now dials the second figure of the code, setting the second selector SS to the corresponding level, whereupon it automatically picks out an idle trunkin this 6 terminate. Assuming now that the calling line hasbeen extended to an idle trunk, shown in Fig. 6, relay A 'thereat operates over the calling line-loop andoperates slow relay B. Relay B in attracting its upper armature grounds tlie'test wire 007 leading ack in the direction of the calling line, this ground maintaining a switching relay at the second selector SS such as D, and relay D of the first selectorandthe holding winding 50% of the line switch operated to prevent release, in the well known manner. Relay B in attracting its lower armature energizes relay 000, which in attracting its armature, lights the calling lamp (301. In response to the lighting of this lamp, the operator in serts plug 700, Fig. 7, into the jack 602 whereupon cutotl relay 603 operates opening the circuit ot relay 600 to extinguish the calling lamp.v clay 703 also operates in this circuit to prepare a circuit for the supervisory lamp a, which circuit however, is simultaneously opened by relay 705 through the closure of the following cir- Assuming this trunk to be idle, no

level. In this level'the leads shown in' Fig.

(lllt-f1(?0 pole oi? battery, tip conductor 701 of the cord, tip of the plug 700, tip of the jack (302, tip conduct-or 605 of the trunk, Fig. 6, impedance coil E, relay C, relay D, ring conductor 601i, ring of the jack 602, ring of the plug 700, ring conductor 702 of the cord, relay 705 to the grounded side of the battery. Relay D operates in this circuit and applies ground to the winding of slow relay 153 thus transferring the con trol of the release of the automatic switches to the operator. Belay C does not operate from the talking battery bridged across the cord. The attraction of the left hand armature of relay D also shunts out the primary winding of induction coil 60 i and at its right hand armature disconnects the secondary winding of this coil from the tip conductor 605 of the trunk. The operator now actuates her listening key LK", and asks the calling subscriber his number. She may ascertain for herself the character of the calling line by operating a class tone key CTK. The actuation of this key breaks the circuit previously traced leading over the tip and ring conductors to the trunk circuit of Fig. 6 which releases relay 1). The retraction of the left hand armature 0t relay D removes the shunt from around the primary winding of induction coil 60 i, which primary winding is connected with the sec: ondary winding 520 of the tone coil 521 associated with the line switch Fig. 5. The character of this tone will indicate to the operator the character of the calling line. This tone is transmitted to the operator over the following circuit: free pole of battery, secondary winding 520 oi": the induction coil 521, Fig. 5, holding winding s of the line switch, contact 522 of the line switch, the uppermost armature and front contact of relay D, conductor 517, brush 51], multiple 510, test brush 523, of the second selector, test multiple of the second selector, test wire of the trunk (Fig. 6), upper armature and trout contact of relay B primary winding oi? induction coil 604 to ground. Through the windings of induction coil (304:, this tone is transmitted to the operators head set over the following circuit: grounded lower armature and front contact of 13 the secondary winding of coil 604, the right hand armature and back contact of relay D, tip 605 ot the trunk, tip of the jack 602, tip of the plug 700, tip side 701 of the cord, contact ot'listening key LK the secondary winding of the induction coil 709 associated with the operators head set, the contact of key LK, contact of key CTK, to ground.

Now while the operator holds her class tone key CTK operated, she will take a cord such as shown in Fig. l and dial the number oi the originating or calling station over the switches shown in Figs. 2, 3, and t. The operation of these switches will in this case be exactly the same as previously described to the point where the testing of the line occurs. it will be noted that while the operator has her class tone key operated, the primary winding of the induction coil (304-, Fig. 6, is included in sleeve wire 607 leading to the holding winding 50-t ot the line switch LS, Fig. lVhen the connector of Fig. 4 tests the selected line, the lower low resistance winding of relay G will be in parallel with the holding winding 50% ot' the line switch Ltd. This condition will cause the demagnetization ot the holding winding 50 i sntticii-intly to relase the line switch. The line switch in releasing, releases the bridged relay if in the trunk, Fig. (5 which in retracting its lower armature opens one of the alternative circuits through the slow releasing relay 1%" and since the class tone key is now operated and relay D inert, the alternative circuit for slow relay B to ground at the armature and front contact of relay D is opened. Relay therefore releases. In retracting its upper armature it removes ground from the sleeve wire 00? leading back to the second and first selectors which releases the switching relays thereat, thereby causing the switches to be restored. The release circuit of the first selector is as follows: free pole of battery re lease magnet 525, 05 normal contact 526, lower armature and contact of relays F, E and D to ground. A similar circuit is closed at the second selector which causes its restoration. The result of these operations is that the original connection to the recording operators position is released and the line is now maintained busy from the connector due to a ground applied to the sleeve multiple 430, Fig. 4, as follows: armature 4:05 and front contact of relay C", sleeve conductor 40?, armature i i2 and back contact of relay G, upper winding of relay J armature and back contact of I, sleere brush 42.), sleeve multiple 430. The switch remains in this condition until the connection has been built up in the other direction to the distant called subscriber. When this subscriber has responded, the operator will actuate her ringing key K, Fig. 1, which will start the automatic ringing operation of the connector, Fig. 4, as previously described.

It will be noted that when the connector selects the line and before slow relay 1" releases to close the circuit ot relay 5" as described a low resistance shunt 1-61 is connected by relays C" and H around the line relay ot the called line to prevent this relay from energizing and again operating the line switch which it would otherwise do after the line switch is released by the shunting of the holding winding. The low re sistance shunt referred to includes a normal contact of test relay J". It will be remembered that the test multiple of the calling tweet line was grounded when the line switch of Fig. 5 extended the calling line to' the firstselector. This ground is applied at the upper armature and front contact of relay F 5 (Fig. 5). Due to this ground connection relay J 4 (Fig. 4) is not operated when the connector selects the line, and consequently the shunt about the holding winding 504, of the line switch (Fig. 5) is closed. As soon as the line switch releases, however, the said ground is removed and relay J operates as described through its upper winding and conductor 550, (Fig. 5) to battery through the cut cit winding 504 of the line switch. The cut on winding opens" springs 501, 502 without plunging the line switch, in the well known manner. The operator may pull out the plug 700'from the jack 602 as soonas the lamp 108 is extinguished due to the re sponse of the called party.

A. call from the mammal paz station to (may other local station.

It will be understood that some of the stations maybe manual stations, i. e. not equipped with dials S at the substation. Lines of this character terminate in line switches which have access to trunks terminating directly in jacks as 602 before the pay station operators whose positions are equipped with plugs similar to those of the operators positions shown in Fig. 7 A call of this character would be handled as follows: the removal of the receiver by the calling party will cause the line switch to seize a preselected trunk terminating'in a jack 602, Fig. 6, whereupon the relay AS operates over the calling line' circuit energizing the slow relay B which causes the relay 600 to operate and light the calling lamp 601 as described.

From this point the operation is exactly the same as previously described up to the point where the operator, bypressing her class tone key CTK, learns the character of the calling line. In this class of calls, how ever, she immediately releases the class tone key and, if the desired subscriber is an automatic subscriber, she will insert the plug 7 10 into a jack 750 terminating in a line switch (not shown) and operate her dial key DYK The shifting of the springs 711 and 712 to.

their alternate contacts bridges the dial I) across the outgoing tip and ring conductors which operates the line relav' of the line switch to operate the pull down winding in the well known manner, to cause the ,line switch to seize a preselected selector the impulse relay of which then operates over the loop including the dial D The operator will then by me'ans'ofher dial build up a connection. to the desired line over local selector switches as shown for eXample in Patent l,3 7fl,22o,issued May 10, .1921, to A. J. Seymour, the last oneofwhich will seize an idle combination local and toll connector shown in Fig. 4. Assumingflheretore, that the connection has been'extended from the cord shown -inFig. to the connector shown in Fig.4, the impulse relayB isenergized over the following circuit: free pole battery, the upper winding of relay B normal contact of relay A tip multiple 466, over the up side of the talking conductors of theselectors, tip of the plug 710, spring 712 of key D 11 conductor 713, normal contact of the dial, conductor 714, spring 711 and its alternate contact, ring of the plug, over the ring conductors of the selectors, ring multiple 46?, lower normal contact oi relay A lowerwinding'ot relay 13% to ground. Relay B? in operating energizes slow relay C which in attracting armature 405, grounds sleeve wire 407 leading back to the preceding selectors to hold the same set in the well known manner, and to cause this connector to test busy to local second selectorQ The ground applied to the sleeve 40'. by the armature 405 is extended over the following circuitto the sleeve multiple 820' of the toll selectors in, which this, connector appears to render the same busy to testing toll selectors. Grounded armature 405, conductor 407, conductor 40 8, relay F conductor 410, conductor 404, sleeve multiple 320. The operator now transmits thetens digit of the desired number by operating her dial D. Upon each retraction of the armature of relay B 4. of the connector, a circuit is closed through the vertical magnet 424, this circuit being .as followsi grounded armature and baclrcontact of relay Bt, armature 420 and front contactof relay C armature 421 and front contact of relay D", conductor 452, armature 423 and back contact of relay J magnet 424to battery. will be noted that this'circuit is exactly the same as that traced when the connector was set from the toll selectorbf 3. Relay D, as in the ormer case, wasenergized when relay C attracted its lairn'iature 405 and upon the opening out the on normal contact 415 is dependent for" its maintained energization' on the impulses received from the armature and backcontact'jot relay"Bt. Upon the termination of the impulses the retraction of the armature 421 ot'relay D? shifts the stepping circuit to the rotarymagnet which now rotates th e'brushes due to the operator transmitting the units digit of'the wanted number. hen the connector is seized by a local second selector, relays E and F are not energized in the case'when the connector is seized by the toll selector. "The testing and seizure of theselected line is the same as preyiously described except that the locking circuit for the relay Gfllwhich is closed it the line is busy, extends over the armature 430 and heel; contact of relay Et, conductor 46 3 conductor 408,conductor 407 to the down the connection by pulling out the plug 710. This is 1n accordance with standard practice. If the line is idle, however, relay ,1 energizes as described when the connector was seized from the toll selector, and at its armatures 445 and 444 applies ringing current to the selected line. lvhen the called subscriber answers, the following circuit is closed to operate the ringing cutoff relay D free pole ringing generator 447, armature 3 and back contact of relay F, arnniture and back contact of relay D, ring side of the line 458, armature 444 and front con tact of relay J brush 457, multiple 456, ring side of the subscribers line, through the substation loop returning over the tip side of the line, multiple 455, brush 454, armature 4-15 and front contact of relay J, tip conductor 458, armature 450 and back contact of relay D", armature 451 and back contact of relay Ff, upper winding of relay D to free pole battery. Relay D in attracting its armature 449 cuts off the ringing current and in attracting this armature and armature 450 connects the incoming and outgoing tip and ring conductors together. In attracting its armature 467, it locks itself up by its lower winding and armature 468 of relay J to ground. Relay A now energizes over the called substation loop as follows: free pole battery, upper winding of relay A conductor 46S), tip conductor 470, armature and front contact of relay D tip conductor 453, armature 445 and front contact of relay J, brush 454, multiple 455, tip conductor of the called line, through the telephonic line of the substation, returning over the ring conductor, multiple 456, brush 457 armature 444 and front contact of relay J ring conductor 458, armature 449 and front contact of relay D conductor 471, armature 472 and back contact of relay G conductor 473, lower winding of relay A armature 467 and front contact of relay D armature 468 and front contactof J to ground. Relay A. in operating reverses the direction of the current in the tip and ring conductors leading back to the operators cord in the well known manner, which operates polarized relay 715 thereat. This relay, in operating, opens the circuit of the calling supervisory lam 716. It is noted in this connection that the sleeve relay 717 is marginal and does not ate to cut off the polarized relay 715 and substitute an ordinary supervisory relay 718 when the plug is inserted in a jack 751 leading to a manual line. The sleeve relay 7'19 operates when the plug is inserted in either jack. The operator may now require the deposit of the coins and actuate collect key (7 K which closes the following circuit including a 110 volt. source of positive current to operate the polarized relay C, Fig. 6, which will in turn apply current from a positive 110 volt source to the calling line to operate polarized magnet l at the calling substation to collect the coins or coin. The circuit for operating relay C" is as follows: positive pole of the generator. alternate contact of coin collect key C K tip conductor 761, tip of the plug 700, tip of the jack 641B, tip conductor 605 of the trunk, upper armature and front contact of relay A", polarized relay U", relay 1), ring conductor (306 of the trunk, ring of the jack 602, ring of the plug 700, ring conductor 702 of the cord, alto"- nate contact of key UK" to ground. The circuit for operating polarized relay P in the substation coin box is as follows: positive side of the generator, contact 608, contact 609, tip conductor G10, tip conductor 530 of the calling line. Positive current is also connected over contact 620 to the ring side of the line. This current passes over the sides of the line. in parallel to ground through the polarized relay P which is connected in a grounded branch. Relay P in responding to this current collects the coin and disconnects itself from ground as described in detail in said Forsberg patent. If the coins are to be returned the operator actuates refund key RK which operates relay C in the opposite direction closing the following circuit to impress negative current on the calling line to cause the polarized magnet P to refund: negative generator, contacts 611, 621, 622 to the tip and ring conductors in parallel to ground through polarized relay P at the calling station. The polarized relay in responding to this current causes the refund of the coins to the subscriber. The spring combinations of the polarized relay C, Fig. 6, and 351, 8 are arranged to eliminate annoying clicks in the calling subscribers ear, by simultaneously applying the positive or negative current to both sides of the line as shown and described in Patent No. 1,262,912, issued April 16, 1918, to H. M. Bascom.

The replacement of the receiver by the called subscriber tie-energizes relay A Fig. 4, which reverses the direction of the current flow of the conductors leading back to the cord circuit, Fig. 7 which causes polarized relay 715 to restore, whereupon the lamp 716 is lighted. The operator observing the lighting of this lamp pulls out the plug 710 which restores the automatic switches in the direction of the called line including the connector, Fig. l. The removal of the plug 700 from the jack 602 and the replacen'ient of the receiver by the calling party causes the slow relay B to release and in retracting its upper armature this relay opens the circuit of the line switch LS, restoring the same. If the calling party had not replaced his receiver, the removal of the plug 700 from jack 602 would have caused the lighting of the calling lamp 601 due to the attraction of the armature of relay 600, and the operator would then re-inscrt plug 700 into the jack and ascertain the subsc 'ibers wants.

\Vhat is claimed is:

1. In {1 telephone system, a toll line, a toll operators position, a subscribers line, means whereby the toll operator can control a talking circuit between said lines comprising a cord circuit at the toll operators position, serially related automatic switches, and a trunk conductor separate from the talking circuit extending from the cord circuit for controlling the setting of said switches, pay station mechanism at the subscribers station, and means individual to the cord circuit for controlling said mechanism over said trunk conductor to collect or refund deposited coins.

2. In a telephone system, a toll line, a toll oporators position, subscribers lines, means whereby the toll operator can establish a talking circuit between the toll line and any subscribersline comprising a cord circuit at the toll opera'tors position, a plurality of serially related automatic switches, and means controllable from said cord circuit for setting a series of automatic switches to extend a talking circuit to a wanted subscribers line, pay station mechanism at each subscribefs station, and means controllable from said cord circuit for collecting and refunding coins deposited in the connection subscribers pay station mechanism.

In testimony whereof, I have signed my name to this specification this 17th day of November 1920.

EMIL JAGOBSEN. 

